Acne is a common inflammatory pilosebaceous disease characterized by comedones, papules, pustules, inflamed nodules, superficial pus-filled cysts, and in extreme cases, sinus formation and deep inflammation, sometimes associated with purulent sacs.
The pathogenesis of acne is complex. An interaction between hormones, keratinization, sebum, and bacteria somehow determines the course and severity of the disease. Acne usually begins at puberty when the increase of androgens causes an increase in the size and activity of the pilosebaceous glands. The earliest microscopic change is intrafollicular hyperkeratosis, which leads to restriction of the pilosebaceous follicle with consequent formation of the comedone composed of sebum, keratin, and microorganisms, particularly Propionibacterium acnes. Lipases from Propionibacterium acnes break down triglycerides in the sebum to form free fatty acids (FFA), which irritate the follicular wall. Retention of sebaceous secretions and dilation of the follicle may lead to cyst formation. Rupture of the follicle with release of the contents into the tissues induces an inflammatory reaction which heals with scarring in severe cases.
Acne tends to appear during puberty and to fade away again, usually spontaneously when growth has stopped. Occasionally it is still to be found in older adults. The face, back, and shoulders are the predominant areas affected. Particularly with the face, severe cases can cause alterations resulting in considerable disfigurement with significant psychological burdens for the afflicted person.
Over the years, many compositions have been developed for the treatment or prevention of acne. For example, acne can be treated by topical application of various lotions, salves, and the like or by, for example, localized treatment with sulfur, resorcinol, salicylic acid, benzoyl peroxide, vitamin A acids, retinoic acid, antibiotics such as erythromycin, and the like. Acne has also been treated orally with antibiotics and tretinoin. However, the effectiveness, reliability, and convenience of current treatments have not always met with patient expectations.
Salicylic acid is a long-known anti-acne active ingredient which is believed to cause a reduction in intercellular cohesion of the corneocytes (see C. Huber et al., Arch. Derm. Res. 257, pp. 293-297, 1977). It has also been postulated that salicylic acid works by dissolving the existing keratin plugs, as well as by preventing the formation of new ones. In order to best exert its skin benefits, the ideal anti-acne composition should deliver and retain optimal concentrations of salicylic acid in the stratum corneum with less penetration through the skin and into the general circulation. Also, compliance by the user to a regimen of treatment involving repeated applications is important. However, salicylic acid tends to be somewhat drying and irritating and can often cause peeling, thereby causing individuals to refrain from using salicylic acid products as frequently and copiously as is necessary to obtain an optimum benefit. Thus, user compliance with current salicylic acid compositions is less than ideal.
Benzoyl peroxide has been used as a keratolytic agent and an antibacterial agent in the topical treatment of skin lesions such as acne. See e.g., Levine et al., Ohio State Med. J., 65, 492 (1969); U.S. Pat. No. 3,535,422, to Cox et al., issued Oct. 20, 1970; British Patent Application Nos. 1,185,685, to Fisher, published Mar. 25, 1970; 1,163,004, to Stiefel Laboratories, Inc., published Sep. 4, 1969; and 1,407,937, to Stiefel Laboratories, Inc. published Oct. 1, 1975. The topical application of benzoyl peroxide for skin lesion therapy is thoroughly detailed in the medical literature. See Brogdne et al., Drugs, 4, 417 (1974); Poole et al., Arch Derm., 102, 400 (1972); Eaglstein, Arch Derm., 97, 527 (1968); Pace, Can. Med. Assoc. J., 93,252 (1965); Vasarinsh, Arch. Derm., 98, 183 (1968); Mysliborski et al., AFP, 15, 86 (1977); Nare, Br. J. Clin. Prac, 29, 63 (1975); Fulton et al., Arch. Derm., 1, 10, 83 (1974); and Wilkinson et al., Can. Med. Assoc. J., 95, 28 (1966).
While benzoyl peroxide can be a useful topical treatment of skin lesions from acne, seborrhea, and other conditions, it has the undesirable side effect of being a contact irritant. The irritation associated with benzoyl peroxide therapy has also been detailed in the medical literature cited in the previous paragraph. Additionally, the redness induced by benzoyl peroxide may impair a patient's ability to perceive the improvement in acne condition initially. Accordingly, some patients are denied the benefits of benzoyl peroxide therapy because of the irritation problem. When used in the treatment of acne, benzoyl peroxide produces dryness, exfoliation, increased redness and a decrease in bacterial flora.
Other agents, such as retinoic acid, are used for the treatment of acne. However, retinoic acid can be extremely drying and irritating when applied topically and can adversely affect the structure of the skin. Also, retinoic acid can be administered orally. However, retinoic acid can be teratogenic and have other undesired side effects.
Antibiotic agents, such as erythromycin, clindamycin, tetracycline, and beta lactams have also been used both orally and topically in the treatment of acne. However, as is a problem with the use of most antibiotic agents in general, bacteria can become resistant making the underlying condition more difficult to treat. Resistant strains of Propionibacterium acnes, Staphylococcus aureus, Propionibacterium granulosum, Gardnerella vaginalis and other bacteria involved in acne have begun to emerge. See, e.g., Eady E. A., et al. The effects of acne treatment with a combination of benzoyl peroxide and erythromycin on skin carriage of erythromycin-resistant propionibacteria. Br. J. Dermatol. 1996; 134:107-113; McLean, N. W.; McGroarty, J. A. Appl. Environ. Microbiol. 1996, 62(3), 1089-1092; Nagaraja, P. Indian J. Med. Microbiol. 2008, 26(2), 155-157; Tomusiak, A. et al. Ginekol. Pol. 2011, 82(12), 900-904; Eschenbach, D. A. Clin. Infectious Dis. 2007, 44(2), 220-221. Furthermore, bacteria, including resistant strains of bacteria, can also cause further complications such as skin infections, eye infections, bone and joint infections, central nervous system infections, and endocarditis. Therefore, with antibiotic treatments for acne, it would be highly desirable to have effective treatments which are also useful against resistant bacteria. See Tan, A. W. and Tan, H. H., “Acne vulgaris,: a review of antibiotic therapy”, Expert Opin. Pharmacother., 2005 Mar. 6(3), 409-418; Oprica, C. et al., “European surveillance study on the antibiotic susceptibility of Propionibacterium acnes”, Clinical Microbiology and Infection, Volume 11, Number 3, March 2005, pp. 204-312; and Goldstein, E., et al., “Comparative In Vitro Activities of retapamulin (SB-275833) against 141 Clinical isolates of propionibacterium spp., Including 117 P. acnes Isolates”, Antimicrobial Agents and Chemotherapy, Jan. 2006, p. 379-381, vol. 50, no. 1.
From the foregoing, and especially in view of the development of resistant strains of bacteria, it is seen that there is a continuing need for safe, effective, and convenient means for treating, preventing, or reducing the risk of acne and other skin infections caused or mediated by Propionibacterium acnes, Staphylococcus aureus, or Gardneralla vaginalis. 
Bacterial vaginosis (BV) is one of the most common vaginal diseases in women of reproductive age. Since BV is caused by an imbalance of normal vaginal microorganisms, there are multiple risk factors, including the use of intrauterine devices, the use of douches, and new sexual partners. Gardnerella vaginalis is a causative agent of BV. BV may present with a burning sensation when urinating and white or gray discharge with a fish-like odor. Additionally, BV can increase the risk of contracting sexually transmitted diseases, including HIV/AIDS. Treatment of BV with current antibiotics has high rates of failure and recurrence. Thus, it is important for there to be safe, effective, and convenient alternatives for treating, preventing, or reducing the risk of BV.
The present invention provides methods for treating, preventing, and reducing the risk of acne and other skin infections caused or mediated by Propionibacterium acnes, Gardnerella vaginalis, or Staphylococcus aureus, in a patient by administering a safe and effective amount of an antibiotic compound, e.g., a topically applied oxazolidinone compound.